class Thing:
    def __init__(self, hp):
        self.hp = hp

    def damage(self, hp):
        raise NotImplemented


class Grenade:
    def __init__(self, atk_hp):
        self.atk_hp = atk_hp

    def attack(self, *args):
        for item in args:
            if isinstance(item, Thing):
                item.damage(self.atk_hp)


class Player(Thing):
    def __init__(self, hp):
        super().__init__(hp)

    def damage(self, hp):
        self.hp -= hp


class Duck(Thing):

    def damage(self, hp):
        self.hp -= hp


grenade = Grenade(100)
player = Player(1000)
duck = Duck(100)
grenade.attack(player, duck)
print(player.hp)
print(duck.hp)
